First years

By 1979, NBC had fallen to third place in the Nielsen ratings. Network executive Fred Silverman, who previously led ABC and CBS to the top of the ratings, joined the network a year earlier, however, he could not bring the same ratings success he had as programming whiz at the latter two networks, resulting in a string of new programs that were derided by critics and eventually being canceled after a few showings. The 1980-81 television season was the low point for NBC; as the network had only three shows in the Nielsen top 20 (one of them, Diff'rent Strokes, would enter NBC's Thursday night lineup for the 1981-82 season). Silverman would leave NBC in the summer of 1981; and was replaced by Brandon Tartikoff. Starting with the 1981-82 season, situation comedies would enter NBC's Thursday programming, such as Diff'rent Strokes, Harper Valley, and newcomers Gimme a Break! and Lewis & Clark (the latter was canceled after one season).

Success in the 1980s

Branding the quality Thursday night lineup began during the 1982-83 season, which NBC promoted Fame, Hill Street Blues, Taxi (after being canceled by ABC after its fourth season) and new arrival Cheers, as "America's Best Night of Television on Television". When the season ended, Fame and Taxi were canceled, with the former being later revived in first-run syndication. However, though Cheers disappointed on ratings during its first season (74th out of 77 shows in that year's ratings), it was critically acclaimed, mostly due to its early success at the Primetime Emmy Awards, and Tartikoff decided to renew the show for a second season, which would premiere during the 1983-84 season, which saw none of its nine fall shows being renewed for a second season (one of them, the short-lived sitcom We Got It Made, premiered on Thursdays during most of its first season until January 1984, and later was revived for syndication). NBC decided to move both Family Ties and Buffalo Bill from Wednesdays to Thursdays during the winter of 1984, joining Cheers, Hill Street Blues and Gimme a Break!, with newcomer Night Court joining the lineup during the summer.

What marked the beginning of NBC's dominance on Thursday nights was during the 1984-85 season, when the network premiered a new show to lead that evening: The Cosby Show, receiving critical acclaim, with TV Guide listing the series as "TV's biggest hit in the 1980s", adding it "almost single-handedly revived the sitcom genre and NBC's ratings fortunes".^[3] The enormous success of Cosby (which became the third-most watched show of the season in the US) also helped the other shows on its Thursday night lineup increase its ratings dramatically, with Family Ties entering the top-ten for the first time; and Cheers and Night Court both entering the top-twenty; while Hill Street Blues remained steadily on the top-thirty. When Cosby debuted, it marked a major turning point for NBC as well, as the network rose to second place at the end of the season; and reached first place at the end of the 1985-86 season, with Cosby being the number-one show in the United States, which it managed to stay on that position for four more seasons until 1990.

As the decade was progressing, NBC decided to move some of their most successful shows to make room for new freshman hits. Hill Street Blues, which enjoyed success during most of its run on Thursday nights since its debut, was replaced midway through its seventh and final season, by legal drama L.A. Law, which premiered in 1986 and stayed its entire run at the 10pm slot until its end in 1994, becoming a runaway success for the network. Other hits on NBC Thursday nights included Cosby spinoff A Different World (premiered in 1987 and replaced Family Ties, which was moved to Sunday nights that year until its end in 1989), and Dear John, Judd Hirsch's starring vehicle after Taxi (premiered in 1988 and replaced Night Court, which was moved to Wednesday nights that year until its end in 1992). Eventually, Dear John, then on its second season, was moved to Wednesdays (alongside Night Court) and was replaced by the sitcom Grand, which premiered in 1990, but enjoyed moderate success, and was canceled by NBC at the end of the year after two abbreviated seasons. That same year, a mid-season replacement, Wings (created by Cheers producers David Angell, Peter Casey, and David Lee) saw its debut, and began to enjoy popularity among viewers on Thursday nights in the following years. As a result of this, NBC ended the 1980s decade as the number-one network on both Thursday nights and overall.

Early 1990s doldrums

However, that dominance during the 1980s, would begin to fade by the start of the 1990-91 season, as the growing popularity of ABC Tuesday and Friday night lineups and Fox's decision to move freshman hit The Simpsons to Thursdays to compete with Cosby partly contributed to its decline. Cosby slipped down to fifth place, while Cheers reached number one on the Nielsen ratings for the first time; however, NBC itself, dropped to second place behind a resurgent ABC. The 1991-92 and 1992-93 seasons were two of NBC's weakest, as the network dropped to third place (behind CBS and ABC) for the first time since 1983. Ratings for The Cosby Show and A Different World decreased considerably and both were no longer inside the top-ten; while Wings continue to rise in popularity, entering the top-20 for the first time. Meanwhile, Cheers became the only NBC show (both in sitcoms and overall) to remain in the top-ten during the 1991-92 and 1992-93 seasons. As a result of its declining ratings, Cosby ended its run in 1992; while A Different World bid farewell in 1993. That year, Seinfeld, which initially struggled from its debut in 1989 as a summer series, was moved from Wednesdays to Thursdays to join Wings and Cheers, with the latter series ending in May after 11 seasons, with its series finale being the second-highest-rated series finale of all-time behind the series finale of M*A*S*H and the highest-rated episode of the 1992–93 season in the US.^[4][5]

Must See TV

The "Must See" slogan was created by Dan Holm, an NBC promotional producer, during a network promo brainstorming session in June 1993 at NBC's West Coast headquarters in Burbank, California. "Must See TV" made its first appearance in NBC promotions in August 1993 and included the day of the week: "Must See TV Thursday". In late summer of 1993, NBC wanted viewers to tune in an hour prior to Seinfeld, and created the "Must See TV" slogan to brand the comedy block. The first "Must See TV" block promo aired during late summer repeats and promoted Mad About You, Wings, Seinfeld and the then-recently-ended Cheers, which also previewed the fall premiere of its spin-off, Frasier. The advertisement ended with the sentence "Get home early for Must See TV Thursday." The "Must See TV" slogan continued in every NBC Thursday night comedy promo throughout the 1993-94 television season to promote the 8–10 p.m. comedy block. The next season, Frasier and Wings were moved to Tuesday nights, with NBC expanding the "Must See TV" brand to include the Tuesday night comedy block: "Must See TV Tuesday". Meanwhile, the flagship Thursday block acquired two new hits, Friends - which became television's second biggest comedy behind only Seinfeld - and ER, which became the number one drama on television. Seinfeld and ER would end up battling the following four seasons for the honor of number one show, before Seinfeld ended its run in 1998.

On November 3, 1994, NBC's Thursday night lineup featured the "Blackout Thursday" programming stunt, in which three of the four sitcoms on that night's "Must See TV" schedule incorporated a storyline involving a power outage in New York City.^[6] The stunt started with Mad About You episode "Pandora's Box", in which Jamie Buchman (Helen Hunt) accidentally causes the blackout while trying to steal cable; it continued with the Friends episode "The One with the Blackout", featuring a sub-plot in which Chandler Bing (Matthew Perry) is trapped in an ATM vestibule with Victoria's Secret model Jill Goodacre and ended with the Madman of the People episode "Birthday in the Big House" (the Seinfeld episode that followed Friends and preceded Madman, "The Gymnast", did not have a blackout storyline though was promoted as part of the event).

As the lineup includes flagship hits such as Friends and ER, NBC dominated once again Thursday nights for the rest of the 1990s decade, with other shows joining and becoming hits for the network, such as Will & Grace, Caroline in the City, Suddenly Susan, Veronica's Closet and The Single Guy. The series finale of Seinfeld, "The Finale", became the fourth-most watched overall series finale in the US after M*A*S*H, Cheers and The Fugitive,^[7] with its ninth and final season reaching the top of the Nielsen ratings, becoming only the third show finishing its runs at the top of the ratings, following I Love Lucy and The Andy Griffith Show.^[8] Consequently, Friends emerged as NBC's biggest television show after the 1998 Seinfeld final broadcast.

Change and record ratings lows

Prior to the 2013 fall season, NBC cancelled or ended nine of its eleven comedies, including the long-running 30 Rock and The Office, in an effort to broaden its comedy lineup.^[11] In May 2013, NBC picked up three family comedies (The Michael J. Fox Show, Sean Saves the World and Welcome to the Family) and rebranded its Thursday night lineup as "NBC's New Family of Comedies" for the fall season.^[12]

The debut of The Michael J. Fox Show was the lowest-rated Thursday fall comedy series premiere in network history.^[13] One week later, the debut of Welcome to the Family became the new record-holder, with Sean Saves the World ranking as the second lowest ever.^[14]

On October 10, 2013, NBC tied an all-time low on Thursday nights (tied with May 17, 2012), while finishing in fourth place (or combined with programming on Spanish-language network Univision, along with Thursday Night Football on NFL Network and Major League Baseball playoff coverage on TBS, seventh) for the night.^[15] On November 21, 2013, NBC averaged a 1.0 in the adults 18–49 age bracket, its lowest ever in-season average for regularly scheduled programming on the night.^[16] On the same night, The CW defeated the NBC comedy block, a first for the network. All three shows were eventually cancelled (Welcome to the Family was pulled three episodes into its first season, while The Michael J. Fox Show and Sean Saves the World were dropped shortly before the 2014 Winter Olympics; in the case of The Michael J. Fox Show, this was despite NBC giving a 22-episode order for the series prior to its debut) and were replaced by critically acclaimed (though low-rated) Thursday night mainstays Community and Parks and Recreation in January 2014, which were joined by Hollywood Game Night in late February.